9.1.8.1 - Twin and adoption studies Flashcards
What is a twin study and how does it work? (3 points)
A study where twins are compared on a specific trait to see how similar they are - done by comparing concordance rates
If a particular behaviour is entirely genetic, then we expect MZ twins to show 100% concordance
If a particular behaviour is more genetic than environmental, then we would expect MZ twins to show a higher concordance rate than DZ twins
What is the biology behind twin studies? (3 points)
Twins are particularly unique - identical twins developing from one zygote share 100% DNA, whereas fraternal twins share 50% DNA
Allows psychologists to determine the likelihood of both, or one twin inheriting a particular trait
How are twin studies used in psychology? (2 points)
Their use ties in with the ‘nature’ explanation of human behaviour - innate biological factors determining our observable and unobservable traits
Psychologists can use them to determine the probability that a twin pair might inherit a clinical disorder like Sz
What is a real-life example of a twin/adoption study? (3 points)
Peter Neubauer conducted a controversial study where he separated identical triplets/twins at birth
They were adopted by three different families from low, high and middle socioeconomic backgrounds
Done to study the impact of nature v nurture on child development
Why are twin studies important to studying disease?(2 points)
Has helped psychologists to investigate whether:
+ Psychological behaviours like human aggression are ‘hard-wired’ into humans in the same way as genetic factors like a person’s phenotypic eye colour
+ Behaviour is learned due to environmental influences (nurture) including clinical disorders like Sz
Are twin studies generalisable? (2 points)
Generalisability is low - twins are a unique population with a much rarer occurrence within society
Their findings may not be fully representative of adult populations or those siblings who are not twins
Why can twin studies be internally valid? (2 points)
They use objective, quantitative data that can be analysed statistically - genetic similarity can be assigned through DNA testing
Allows cause and effect to be established between the inheritance of a particular gene and the expression of a specific trait
Why can twin studies have decreased internal validity? (2 points)
Quasi-experimental design using a naturally occurring IV - correlation does not always mean causation when studying concordance rates for twin studies
Psychologists may be failing to account for confounding factors
How do adoption studies work? (2 points)
They look at the impact ofnurtureon children raised in a more ‘nurturing’ environment by non-biological foster/carer parents
No biological connection between the foster parent and the child - if the child grows up to share the foster parents’ traits, then these traits are probably produced bynurture, not nature
What is the biology behind adoption studies? (2 points)
Biological parents pass on 50% of their DNA from respective mother and father to offspring
Non biological/foster parents are not biologically related or linked to the child
Why are adoption studies important to studying disease?(2 points)
They are used in biological psychology to help psychologists investigate whether clinical disorders like Sz are caused by ‘nurture’ (‘schizophrenic mother’) or due to a biological reason
Has helped society to move progressively away from blaming/stigmatizing the mother and towards considering genetics and biology as root causes
How generalisable are adoption studies? (4 points)
Low generalisability - adopted children are not very representative of other children
They have been separated from their biological parents - perhaps through tragic circumstances or because their biological parents “gave them up” due to difficult circumstances
John Bowlbyargues that children are badly affected if they are separated from their mothers during a critical period in infancy
This would make them even less representative of children - unlike the general population of children, they may have experienced childhood trauma
How do adoption studies have high internal validity? (3 points)
They are made more valid if the researchers have information about the child’s biological parent
If the child grows up with traits that resemble the adoptive parent more than the biological parent, this is stronger evidence that these traits are due to nurture
Psychologists conduct them withlarge samples so thatstatistical analysiscan be assessed
How do adoption studies have low internal validity? (3 points)
Correlation does not always mean causation when studying concordance rates for adoption studies
Psychologists may be failing to account for confounding factors
E.g. when comparing the environment the 3 identical strangers were raised in, they had differing relationships with the non-biological father - not entirely standardised
